Process of obtaining absolute propyl alcohol



Jan. 5 1926. 1,568,349

- J. A. STEFFENS' PROCESS OF OBTAINING ABSOLUTE PROPYL ALCOHOL Filed April 5, 1921 5 z 11 1/ I Z Patented Jan. 5, 1926.

UNITED STATES PATENT OFFICE.

JOHN A. STEFFENS, OF BALTIMORE, MARYLAND, ASSIGNOR TO U. S. INDUSTRIAL ALCOHOL 00., A CORPORATION OF WEST VIRGINIA.

PROCESS OF OBTAINING ABSOLUTE PROPYL ALCOHOL.

Application filed April 5, 1921. Serial No. 458,835.

To all whom it may concern:

Be it known that I, JOHN A. STEFFENS, a citizen of the United States, residing at Baltimore, State of Maryland, have invented .a certain new and useful Improvement in Processes of Obtaining Absolute Propyl Alcohol, of which the following is a specification.

My invention relates particularly to a process of removing water from propyl alcohols but it has reference especially to the production of absolute propyl alcohol.

The object of my invention is to provide aprocess whereby the propyl alcohols, that is to say normal propyl alcohol or isop-ropyl alcohol, may be separated from the water contained therein and so that, if desired, ab-

solute propyl alcohol may be obtained in accordance with a commercially practicable system.

More particularly, the object of my invention is to provide a process based upon the utilization of a third liquid which is miscible with the propyl alcohol but substa tially immiscible with water and which is of such a character that when the three constituents are present vapors of the same are evolved by distillation, containing a considerable percentage of water and the third liquid so that all of the water and the third liquid may be removed in this Way from the residual constituent which is the alcohol. The evolved vapors are comprised of a ternary mixture of the three constituents. This third liquid may be any one of a number of diiferentcompounds, such, for example, as benzol, carbon tetrachloride, hexane, etc., but I prefer to use benzol.

One of the objects of my invention is to avoid the necessity of using a large amount of benzol in carrying out the process.

A further object is to so arrange the process as to enable a close regulation thereof to be obtained, inasmuch as in my process the dehydration of the propyl alcohol is carried out in a column, the upper portion of which is fed continually with a quantity of the condensatev of fixed composition passing out of the top of the tower, and as a condensate rich in water is obtained with a comparatively small load being placed upon the auxiliary apparatus and as the propyl alcohol evolved in the form of vapor is re turned to the tower continually in the fornr of 'a liquid having a fixed composition obtained by a uniform rectification of the recovered propyl alcohol.

A further object is to so arrange the system as to enable the several operations to be carried out continuously, but so that the several operations may be carried out largely independently of the remaining operations, thus enabling the operator of the system to recover-Vin case at any time any one of the operations does not function. By reason of these features in my process the system may be operated continuously.

Further objects will appear from the detailed description thereof contained hereinafter.

While my invention is capable of embodiment in many different forms, for the purpose of illustration I shall describe only certain ways in which my invention may be carried out, and while my invention is capable of being carried out in connection with many different types of apparatus, I have shown only one form of the same in the accompanying drawings, in which- The figure is a diagrammatic representation of an apparatus which may be used in connection with my invention.

In the drawings, I have shown a valved inlet pipe 1 for feeding continuously into the apparatus isopropyl alcohol and which may, for example, have a strength of 88%. Leading into the pipe 1 there is a valved supply pipe 2 for sup-plying initially the desired quantity of the third liquid, as, for example, benzol, and for supplying to the system additional amounts of benzol to replace the small quantities thereof which are lost by evaporation therefrom. The propyl alcohol and benzol ar fed to the system in proportions such that in the system, at any given time, there would be approximately equal parts by weight of propyl alcohol and benzol therein but preferably a slightly smaller quantity of the benzol than of the propyl alcohol. The valved pipe 1 leads into a tail-box 3 which is connected by a liquid sealed pipe 4 to a dehydrating column 5 which is constructed in any suitable man? ner but which may have, for example, a plurality of plates the same as in the case of the usual ethyl alcohol rectifying column. The column 5 has at the bottom an inlet 6 for steam for heating the column indirectly.

' Vapors are evolved from the column com: prising approximately 12% by weight of propyl alcohol, 8% by weight of water and 73% by weight of benzol, and absolute propyl alcohol flows from the liquid sealed drain pipe 7. The evolved vapors pass out by means of a pipe 8 into a dephlegmator 9 which is connected by a liquid sealed pipe 10 to the top plate of the column. T e dephlegmator is cooled in the usual way with the aid of water inlet and outlet pipes 11 and 12. The uncondensed vapors from the dephlegmator 9 pass into a condenser 13 through a pipe 13, the temperature in which is at approximately 665 (1., said condenser being cooled by Water passing through lnlet and outlet pipes 14 and 15 and-the condensate therefrom enters a vented sight-glass 16 from which a portion of the condensate passes through a valved pipe 17 to the plpe l0 and thence to the top of the column 5. The main portion of the condensat is conducted by a pipe 18 to a tail-box 19 and thence by a plpe 20 to a separating chamber 21. The liquld received in the separatlng chamber immediately separates into two layers, the upper layer of which is rich in benzol but poor in propyl alcohol and water, while the lower layer is rich in propyl alcohol and Water but poor in benzol. The composition of the respectlve layers 1s approximately as follows: The upper layer contains approximately 79% by welght of benzol, 3% by weight of water, and 18% by weight of propyl alcohol, while the lower layer contains approximately by weight of benzol, 73.5% by weight of water, and 26% by weight of propyl alcohol. Th upper layer is conveyed by a vented pipe 22, having a liquid seal 23, back to the tower 5 while the lower layer passes by a vented plpe 24 to a propyl alcohol rectifying column 25 having a steam inlet pipe 26 in the usual way for indirect heating and a liquid sealed drawofi' pipe 27 for water at the bottom of the column. Th lower portion of the column 25 is maintained at a temperature of just above 100 C. The evolved propyl alcohol vapors containing some water pass out of the top of the column through a pipe 28 to a dephlegmator 29, constructed substantially the same as th dephlegmator 9 and which is arranged to return the condensate therein to the top of the column 25 by a liquid sealed pipe 30. The vapors from the dephlegmator 29 pass through a pip 31, the vapors in which are at a temperature of approximately 0., to a condenser 32 constructedthe same as the condenser 13. The condensate from the condenser 32, which comprises approximately 88% propyl alcohol enters'a vented sight-glass 33 and a portion of the same passes back through a valved pipe 34 to th liquid sealed pipe 38 and thence to the top of the column 25,

While the remainder thereof enters a tailbox 35 and is conveyed therefrom by a valved pipe 36 direct to the liquid sealed pipe 23 and thence to the column 5. The apparatus is also arranged in an elfective 70 manner in that the portions thereof requiring observation are located upon an operating floor 37.

In carrying out my invention the propyl alcohol containing water and benzol is fed into the column 5, the lower portion of which is maintained at a temperature slightly below 825 C. The vapors of propyl alcohol, water and benzol will be distilled from the top of the column 5 thus leaving behind absolute propyl alcohol which passes out of thebottom of the column through the pipe 7. The evolved vapors pass into the dephlegmator 9, whence some of the condensate is returned to the topmost plate in the column 5, and at the same time a small portion of the condensate from the condenser 13 is also conveyed into the tower at the same point, thus sealing the uppermost plates in the column with a liquid of a constant composition and which is very close to the composition of the evolved vapors. This not only provides uniform conditions at the top of the tower but enables the process to be conducted with a comparatively small quantity of benzol so that the condensate reaching the separating chamber 21 will be rich in the water to be removed. When the liquid condensate reaches the separating chamber 21 it immediately divides into two liquid phases forming layers, the upper layer, comprised principally of benzol, being conveyed back to the tower 5, while the lower layer, comprised principally of propyl alcohol and water but containing some benzol, is conducted to the propy alcohol rectifying column 25. This column is required merely to rectify the propyl alcohol, said column at its lower portion being maintained at a temperature of approximately 100 C., the water from which passes out from the bottom of the column, while the propyl alhool is collected as a condensate having a fixed composition which is returned to the column 5. Inasmuch as the propyl alcohol returned to the column 5 has a definite composition and temperature, and as the benzol has been substantially entirely removed therefrom, the conditions in the upper portion of the column 5 are comparatively uni- 129 form so far as the character of the incoming propyl alcohol is concerned. By prowriding a system of this character in which the several parts of the system operate without a great degree of dependence upon one another it is possible to conduct the process with great uniformity of results and in such a way that the failure of any portion of the system to function temporarily would not interfere with the elfective'operation of the 130 system as a whole. For these reasons, fur thermore, it is practicable to obtain absolute propyl alcohol with the process conT tinuously.

While I have described my invention above in detail I wish it to be understood that many changes may be made therein without departing from the spirit of the same.

I claim:

1. The process of obtaining absolute propyl alcohol from aqueous propyl alcohol, which consists in adding a third liquid thereto, miscible with the alcohol but substantially immiscible" with water; distilling the mixture to evolve a ternary constant boiling mixture and leave absolute propyl alcohol as a residue; returning to the top of the rectifier a portion of the evolved distillate as a reflux; condensing the remainder of the distillate and allowing it to separate into two layers; returning to the first named liquid undergoing distillation the layer richer in said third liquid; rectifying the alcoholic layer and'returning to said first named liquid the rectified alcohol.

2. The invention of claim 1 wherein the alcohol is continuously returned with a constant aqueous content.

39The process which comprises continuously rectifying a propyl alcohol, water and a third liquid, miscible with the propyl alcohol but substantially immiscible with water, separating the condensate obtained from the evolved vapors so as to remove therefrom the third liquid, returning the third liquid to the rectifier, rectifying the residue of the condensate, obtaining therefrom a propyl alcohol of a fixed composition and returning the same to the first mentioned rectifier.

4. The process which comprises continuously rectifying a propyl alcohol, water and a third liquid, miscible with the propyl alcohol but substantially immiscible with water, separating the bulk of the condensate obtained from the evolved vapors so as to remove therefrom the third liquid, returning the third liquid to the rectifier, rectifying the residue of the condensate, obtaining therefrom a propyl alcohol of a fixed composition and returning-the same to the first mentioned rectifier, the unseparated ortion of the condensate being returne to the top of the first'mentioned rectifier.

5. The processwhich comprises cont-inuously rectifying a propyl alcohol, water and benzol, separating the condensate obtained from the evolved vapors so as to remove therefrom the benzol, returning the benzolto the rectifier, rectifying the residue of the condensate, obtaining therefrom a propyl alcohol of a fixed composition and returning the same to the first mentioned rectifier, thereby obtaining an absolute propyl alcohol.

6. The process which comprises continuously rectifying a propyl alcohol, water and benzol, separating t e bulk of the'condensate obtained from the evolved vapors so to remove therefrom the benzol, returning the benzol to the rectifier, rectifying the residue of the condensate, obtaining therefrom a propyl alcohol of a fixed composition and returnin the same to the first mentioned rectifier, t e unseparated portion of the condensate being returned to the top of the first mentioned rectifier, thereby obtainit in liquid form to the column near the top thereof.

9. The process which comprises rectifying in a column a propyl alcohol, water, and a third liquid which is miscible with the a1 cohol but substantially immiscible with water, condensing the vapors evolved and returning part thereof to the top of the column, separating the alcohol from the remaining condensate, rectifying it, and returning it to the column below the point of introduction of the aforesaid condensed vapors.

10. The process of manufacturing substantially anhydrous propyl alcohol which comprises rectifying in a column a mixture. of a propyl alcohol. water and a third liquid which is miscible with the alcohol but substantially immiscible with water, condensing the vapors evolved and returning part thereof to the top of the column, separating the alcohol and the third liquid from the remaining condensate, rectifying the alcohol, and returning it in liquid form with the third liquid to the column at a point below the point of introduction of the aforesaid condensate.

11. The process which comprises rectifying propyl alcohol, water, and benzol, separating the alcohol from the vapors evolved, rectifying it, and returning it in liquid form to the rectification process.

In testimony that I claim the foregoing, I have hereunto set my hand this 26th day of January, 1921.

. JOHN A. STEFFENS. 

